Sampling of strip metal by use of die and an opposed shaped charge



Aug. 9, 1960 .H. CRAMER ETAL 2,948,176 SAMPLING 0F swan METAL BY USE OF DIE AND AN OPPOSED SHAPED CHARGE Filed May 23, 1956 1NVENTOR$ CHARLES H. CRAMER EDWARD J. SURRETT JAMES F. SWED ATTORNEY method and apparatus.

n t S ws Pa flw SAMPLING F STRIP METAL BY USE OF DIE AND AN OPPOSED SHAPED CHARGE Charles H. Cramer, Woodbury, N.J'., Edward .J'. Surrett,

Montreal, Quebec, Canada, and James P. Swed, Gibbstown, NJ., assignors to E. I; du. Pontv de. Nemours and Company, Wilmington, Del., a corporation; of Delaware Filed May 25, 1956, so. No. 586,722

Claims. or. 83- -53) The present invention relates to a novel sampling More particularly, the. present invention provides a method and apparatus forrsampling strip metal without requiring interruption ofthe rolling Operations. r

Steel ingots are converted to strip or sheet steel by passing the steel through a sequence of rollers. In the continuous rolling processes, the rollersor mills are so synchronized as to speed that each successivemill takes the strip at exactly the same speed that the preceding mill is delivering. The delivery speed of the last mill is between 2,000 and 3,000 feet per minute. The steelifrorn the last mill is then coiled or cut to. length, flattened, and piled. Steel strip or sheet produced in this manner will have a thickness of between 0.013 inch and. 0.085. inch and a width of two or more feet. In the production of steel strip and sheet, samples must be taken fromthe edge and center in sufficient quantity to provide a true picture of the analysis of the finished strip or sheet.

These samples may be checked for hardness, ductility, grain structure and surface conditions. The size of. samplerequired may range from inch to 3 /2 inches in diameter, depending upon the testsidesired, Normally at least eight samples per hour per mill unit are required, in larger mil-ls this amountsto almost 8'00. samples per day. Because of the thickness of the sheet andthe high delivery speed, no feasible means for obtaining the .sam-

pics from portions other than the ends-ofthe strip without first stopping the sheet or strip has been available. Since 7 all mill units are synchronized, this stoppage of the strip or sheet for sampling would require the stopping'of all production in the'sequence. The slowdown and start-up are timeand power-consuming, so th atpresent practice is totake only end samples, even though they are not necessarily representative of the major proportion of the strip. 7 M

It is an object of this invention to provide a .rnethod V and arrangement for sampling continuouslyrolledv strip and sheets without requiring stoppage of the strip or sheet. Additional objects will become apparent as the invention is more fully described. 7

In accordance with the present invention a sample obtained from a moving strip of steel by positioning ad- 'jacent to one surface a supporting die having a sharpedged well of the peripheral dimensions and contourof 'the desired sample, positioning adjacent to-the opposite surface of said strip and in alignment with said well a cutting charge of a high velocity detonating explosive, "said charge having an outer periphery substantially the surface is provided within the well, whereby the travel h of the severed sample limited.

Patented Aug. '9, 196 0 In order to more adequately describe this invention, reference is now madeto the accompanying drawings which illustrate a specific apparatus. for sampling strip metal following the method of this invention. It will be understood that many variations and modificationscan be made without departure from the essentials .of this invention, and that. the drawings are illustrative only. In the drawings, Figure 1 represents a side .view of the sampling apparatus of this invention in position to take a sample. Figure 2 is a top view of the apparatus, Figure 3 is a detail view of the supporting die portion and the cutter portion of the apparatus, andFigureS 4 and 5' are views of the explosive charge.

Referring now to the figures in greater detail, 1 represents a strip of metal, for example, movingfin "the direction of the arrow shown in Figure, 2, 2 is a housingjor the supporting die 9, 3 is a barricade, for example of steel, around the cutting charge 14, 4 and 5 are support arms individually rotatably mounted on post 6. '7 is a setting indicator used'to position the supporting die 9 and the cutting charge 14 over the portion of strip 1 from which the sample is to be taken.

8 is a die holder within housing 2 which supports the supporting die 9. Within the holder 8 is the sample receiver l0-mountedover-coil spring 11. 12 is a support post'to' which charge holder 13 is attached, and 14 is the ground. The initiator 15 is wedged in a recess at the edge of charge holder '13, a snap-fit being thus provided.

The operation of the apparatus depicted is as follows. The annular cutting charge 14 is slipped over the-end of charge holder '13-, initiator 15- is snapped place in the recess incharge holder'13, and leg wire 16 is connected to. lead in wire 17. Support arms 4 will have been rotated topositi'onbarricade 3 alongside of the. moving strip to permit ready access for the loading operation. Support arms 5- may also have been rotated to position housing 2 alongside of themoving strip 1 to facilitate removal of V the sample from the previous operations. -The arrns4 and -5 may be independentlyrotatable, and, if desired, can

and barricade 3 are positioned in alignment with each other over a predetermined port-ion of the moving strip by rotation .of support arms 4. and 5 Indicator 7' permits exact positioning of the supporting and cutter units, i.e

the. die. 9 .and the charge 14 with respect to the strip 1.

When desired, initiator 15 is actuated by application of an electrical 'firing current, and produces detonation of cutting charge .14. The. explosive pressures generated by the detonation drive the strip 1 tightly against the-supporting die 9. The yieldab'le sample receiver 10 permits the tremendous pressuresover the strip to :force a porztion ofthe strip into the well in supporting die 9, the' portion conforming to the contour and dimension of the well. The supporting surface provided by the portion of the supportingdie-9 surrounding the well prevents any deformation orburringof the remainder of the strip. The

force of the explosion will press sample receiver-lll-down against the resistance of coil springll, and themoving strip will cover the well in supporting die 9 ibefore'the sample is raised to'a point where it contacts the sheet, 1

The charge holder 13 also serves to provide confinethus increasing the downward pressure on the area of the strip 1 over the well in supporting die 9. The barricade 3 serves as a barrier against any fragments and as a muffler to reduce the noise produced by the detonation.

In the embodiment illustrated, cutting charge 14 is shown as an annular ring. For heavier strip sampling, a cup-shape wherein the bottom is of thin cross-section compared to the walls may be used, or the charge may be in the form of a wheel having two or more spokes of explosive radiating from the center. In such cases, initiation would preferably be provided at the center. As previously indicated, the best results are obtained when the greatest concentration of explosive is in the periphery of the charge. The amount of explosive required will depend on the type of explosive, the type of metal in the strip, the thickness of the strip and the size of the sample desired. If an oval contour, or any other symmetrical contour is desired for the sample, the contour of the charge and the well can be so provided.

The three essential features in the present invention comprise the positioning of a supporting die having a well with sharp edges closely adjacent to the surface of the strip, the positioning of a cutting charge of a high velocity detonating explosive adjacent to the opposite surface of the strip and in alignment with the well in the supporting die, the charge having a peripheral contour and dimension substantially the same as that of the well, and the initiation of the cutting charge. The detonation of the charge will punch out a sample having approximately the contour and dimensions of the well in the supporting die.

The velocity imparted by the detonation of the cutting charge to the sample is sur'licient to cause it to act as a projectile if no receiver is provided. By positioning the receiver within the well closely adjacent to the strip being cut, the sample can be recovered readily, and no deformation of the major portion of the sample can occur. If the receiver is positioned a substantial distance from the cutting edge of the die, the sample may acquire sufficient velocity to make its retrieval in undistorted form difficult. However, the method of this invention is not dependent upon any particular construction or location of the sample receiver. The spring-loaded receiver illustrated in Figure 3 represents a prefererd embodiment.

The detonation of the cutting charge adjacent to the surface of the sheet will produce the punching action in the absence of any confinement above the central portion of the charge. It has been found, however, that the sample may be lifted out of the well in the supporting die by the forces of detonation and actually hurled upwardly. The presence of a substantial mass over the central portion provides confinement for the explosive gases and prevents such action.

The initiator used to detonate the cutting charge may be a conventional electric blasting cap or may be specially designed for'this purpose to facilitate installation. The positioning of the initiator in detonating relationship to the cutting charge can be done in a variety of arrangements.

The cutting charge will preferably consist of a detonating explosive, such as PETN, RDX, or cyclotetramethylenetetranitramine; however, other compositions of sufficient sensitivity and propagating ability, such as dynamite compositions, may be used. The charge may be prepared by packaging the explosive in a rigid container, such as a plastic or paper-board container, or the explosive may be compounded with a binder to produce a charge which does not require packaging. The positioning of the cutting charge in alignment with the Well in the supporting die is facilitated by the use of a charge support such 'as shown in Figure 3. The charge support will preferably be replaceable because deformation from repeated detonation of the cutting charge will occur. Many modifications of the charge-holding element can be made, and its design will depend largely on the type and size of charge used.

The well or opening in the supporting die must have a sharp edge in order that the sample be cleanly cut from the strip. Therefore, the die should be readily replaceable, and should be prepared from a wear-resistant steel.

In the embodiment shown, the die is a simple sleeve,'and

this represents a preferred form. The diameter and contour of the Well is entirely dependent upon the desired diameter and contour of the sample. Generally, a circular sample from two to three inches in diameter is desired.

The spacing between the cutting charge and the surface of the die will preferably be as small as free movement of the strip will allow, i.e., the minimum spacing will be only slightly larger than the thickness of the strip. Explosive force is dissipated when the cutting charge is positioned a substantial distance away from the sheet, and irregularities in the cutting action occur if the die is positioned a substantial distance from the sheet. Generally speaking, the spacing between the bottom of the cutting charge and the surface of the die should not exceed twenty times the thickness of the sheet.

The alignment of the cutting charge and the well in the supporting die can be provided by a number of conventional means, such as by means of interlocks, by special gearing, by visual alignment of angle indicators, etc. Alternatively, arrangement may be made to fire the charge automatically when the two elements move into alignment. Such arrangement would permit positioning one unit at the desired sampling location and swinging the other unit across this location.

The present invention has been described in detail in the foregoing. Because the invention is susceptible to many modifications and variations by the exercise of ordinary skill, we intend to be limited only by the following' claims:

We claim:

1. A method for removing a sample from a moving metal strip which comprises positioning closely adjacent to one surface of said strip a supporting die having a sharp-edged well of the peripheral dimensions and contours of the desired sample, positioning adjacent to the opposite surface of said strip and in alignment with said well a cutting charge of a high velocity detonating explosive, said charge having essentially the same dimension and contour as said well and comprising means for concentrating the explosive effect of said charge above and around the periphery of said well, and thereafter detonating said explosive charge and thereby creating a force concentrated on the upper side of said metal strip directly above and around the entire periphery of said well.

2. A method as claimed in claim 1, comprising positioning the said cutting charge between a confining mass and said strip.

3. Apparatus for removing a sample from a moving metal strip comprising a supporting die having a well of the dimensions and contour of the desired sample, a cutting charge of a high velocity detonating explosive of essentially the same dimension and contour as said well in alignment with said well and spaced from the top of said well a distance equal to at least the thickness of said stn'p, said cutting charge comprising means for concentrating its explosive effect above and around the periphery of said well, a support element for positioning said cutting charge, a housing surrounding said support element, and a sample receiver disposed within said well.

4. Apparatus according to claim 3, wherein said cutting charge is annular in form.

5. A method of claim 1 in which the metal strip is moving between the supporting die and the cutting charge at a rate of about 2,000 to 3,000 feet per minute.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Mohaupt Mar. 21, 1950 Harris et a1 Mar. 31, 1925 Klause Oct. 22, 1935 Sabo Dec. 21, 1937 Henry Dec. 3, 1940 6 Temple Mar. 10, 1942 Davis Feb. 18, 1947 Byers June 27, 1950 Muddiman Mar. 27, 1951 Grandin Aug. 14, 1956 Long July 16, 1957 Norman Sept. 23, 1958 

